A new type of pH-responsive indole-based (4-HINF) hydrogel, fabricated by a sol–gel method, was utilized as a platform for colorimetric detection of urea in aqueous solution.
Poly-aluminum silicate sulphate (PASS) was synthesized in a mixed aqueous solution of sodium silicate and aluminum silicate via a sol–gel method for use in ultra-low density fiberboard (ULDF).